<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    var arr = ['q', 'w', 'e']

    // 转换成字符串
    // console.log( arr.toString() )  // q,w,e

    console.log( arr.join('!') )  // q!w!e
    console.log( arr.join('999') )  // q999w999e
  </script>
</body>
</html>